The common clinical causes of premature loss of milk teeth are mainly the following: 1, due to severe caries and its resulting pulp disease and periapical lesions, if not effectively controlled, the milk teeth are repeatedly inflamed and are extracted early considering the impact on the inherited permanent tooth embryo; 2, the ectopic eruption of permanent teeth, including the eruption of multiple teeth, which causes premature resorption, loosening and loss of milk tooth roots; 3, trauma to milk teeth. Premature loss of milk teeth generally occurs in two cases, on the one hand, because of trauma resulting in the total loss of the anterior milk teeth, when replantation is generally not considered. The traumatic embedding of the milk tooth, especially when the crown is displaced to the labial side and the root is displaced to the palatal side, affects the permanent tooth embryo and is extracted; 4, invasive periodontitis in childhood, this is more rare and can involve the whole mouth of the milk tooth, acute inflammation of the gums, rapid periodontal destruction, often leading to premature tooth loss; 5, the milk tooth is congenitally missing teeth; 6, rare genetic syndromes in childhood can also lead to premature loss of the milk tooth , such as hypophosphatasia, palmar toe keratosis periodontalis syndrome, etc.